When taking into account the Tax Cuts and Jobs Act for 2018, don’t focus solely on the federal 21% flat tax rate on the C-Corp level. There are plenty of other taxes, including capital gains taxes on qualified dividends, state corporate taxes in 44 states, and accumulated earnings tax assessed on excess retained earnings.

Starting in 2018 under the new tax law, C-Corps may benefit from a 21% flat tax rate vs. individual graduated rates of 10% to 37%. Don’t confuse your tax bracket with your tax rate, which is less. For example, the average individual tax rate is 27% for a married couple entering the top 37% tax bracket of $600,000 and 30% for a single filer approaching the top bracket of $500,000; so the actual rate difference is 6% and 9% in these two examples.

Upper-income traders may also have individual 3.8% net investment tax (NIT) on net investment income (NII). NIT applies on NII over the modified AGI threshold of $250,000 (married) and $200,000 (single). Adding this in, the difference between the flat rate could be 9.8% and 12.8% in our example.

Traders don’t owe self-employment (SE) tax, so I don’t factor that into the equation. Other small business owners have SE or payroll tax in pass-throughs but can avoid it with a C-Corp. Let say the C-Corp has a 10% rate advantage for high-income traders and a lower or no benefit for middle- to lower-income traders.

Now come all the haircuts that can lead to adverse taxes and make the C-Corp a costlier choice for a trader. Double taxation on the federal level can wipe out that savings with a 15% or 20% capital gains tax on “qualified dividends.” Double taxation on the state level can lead to a C-Corp owner paying higher taxes than with a pass-through entity. There are potential 20% accumulated earnings taxes and personal holding company tax penalties. Look before you leap into a C-Corp and consult a trader tax expert.

C-Corp double taxation with qualified dividends

A C-Corp pays taxes first on the entity level, and the owners owe taxes a second time on the individual level on dividends and capital gains.

When C-Corps make a cash or property distribution to owners, it’s a taxable dividend if there are “earnings and profits” (E&P). If the individual holds the C-Corp stock for 60 days, it’s a “qualified dividend,” subject to lower long-term capital gains rates of 0%, 15%, and 20%. The 0% capital gains bracket applies to taxable income up to $77,200 (married) and $38,600 (single). A 15% dividends tax offsets the difference in individual vs. corporate tax rates.

State double taxation can ruin the C-Corp strategy

According to Tax Foundation, “Forty-four states levy a corporate income tax. Rates range from 3 percent in North Carolina to 12 percent in Iowa.” (See your state on the Tax Foundation map,State Corporate Income Tax Rates and Brackets for 2017.) States don’t use lower capital gains rates for taxing individuals; they treat qualified dividends as ordinary income.

A C-Corp is a wrong choice for a trader entity in California with an 8.84% corporate tax rate, but it could be the right choice for a high-income trader in Texas without corporate taxes if he or she retains earnings and can successfully avoid IRS 20% accumulated earnings tax (more on this to come). The Texas 0.75% franchise tax applies to all types of companies with limited liability, including LLCs, and C-Corps, and the “No Tax Due Threshold” is $1.11 million. Most traders won’t trigger the Texas franchise tax.

Don’t try to avoid filing a C-Corp tax return in your resident state. You are entitled to form your entity in a tax-free state, like Delaware, but your home state probably requires registration of a “foreign entity,” if it operates in your state. Setting up a mail forwarding service in a tax-free state does not achieve nexus, whereas, conducting a trading business from your resident state does.

The new tax law capped state and local income, sales, and property taxes (SALT) itemized deductions at $10,000 per year. It does not suspend SALT deductions paid by C-Corps, but that expense is only the double-taxed portion; the individual SALT on qualified dividends is still limited.

Accumulated earnings tax

If the C-Corp does not pay dividends from E&P, the IRS can assess a 20% “accumulated earnings tax” (AET) if the C-Corp E&P exceeds a threshold and company management cannot justify a business need for retaining E&P. The IRS is trying to incentivize C-Corps to pay dividends to owners. The IRS AET threshold is $250,000, or $150,000 for a personal service corporation. (See Section 533.)

If the IRS treats a trader tax status (TTS) trading company as an “investment company,” then it may assess 20% AET on all E&P and therefore undermine the C-Corp strategy for traders. But I don’t think a TTS trading company with Section 475 ordinary income is an investment company. A TTS trading C-Corp needs to demonstrate a business need for E&P above the $250,000 threshold.

“AET requires the corporation to have adopted a plan for business expansion that will require substantial additional capital,” says Roger Lorence, a tax attorney in the New York City area who specializes in hedge fund tax. “The plan must be in writing and adopted by the Board; it must refer to the analysis of the business, the need for expansion, the need for more capital, and include a timeline for implementation.”